1. Field of the Invention
This invention relates to the preparation of allene from acetone in the presence of an alumina catalyst.
2. Description of the Prior Art
Various methods are known for preparing allene, typically in combination with methyl acetylene. The latter is an isomer of allene and the manufacture of one generally results in the manufacture of the other since the two are in a constant state of equilibrium. U.S. Pat. No. 2,510,550 teaches the manufacture of methyl acetylene from the alcoholysis of magnesium carbide. U.S. Pat. No. 2,649,485 teaches the manufacture of methyl acetylene and allene by subjecting a dihalogenated propane or mono-halogenated propylene to decomposition at a temperature between about 850.degree.-1050.degree. C. U.S. Pat. No. 2,755,319 teaches the manufacture of methyl acetylene by the dechlorination of 1,2-dichloropropane in the presence of sodium hydroxide. U.S. Pat. No. 2,818,456 teaches the preparation of allene by the decomposition of diketene at a temperature between about 510.degree.-590.degree. C. The decomposition is performed in a copper-lined reactor. Still other methods are known. See for example U.S. Pat. Nos. 2,848,520 and 2,925,451.
Various acid and bases have long been known to catalyze a variety of acetone condensation reactions. For example, U.S. Pat. No. 3,497,558 teaches that acetone and 45% aqueous potassium hydroxide heated to a temperature of about 220.degree. C. under antogenous pressure yields mesityl oxide, isophorone and higher molecular weight products. U.S. Pat. No. 3,816,546 teaches the vapor phase condensation of acetone over magnesium oxide to produce 3,5-xylenol.